In the design of splined connecting shafts for attaching auxilliary aircraft equipment to aircraft engines, it has been found that without adequate lubrication the splines rapidly wear, become corroded, and fretted. In the design of such equipment, it is therefore a requirement that a means be found for the adequate lubrication of the splined region. Further, the generator bearing which is generally located in the region of the splines also must receive an adequate source of lubricating oil. Therefore, any system that provides for adequate lubrication of the splines must also consider the lubrication requirements of the bearing.
In spline systems of the type used in aircraft engines at speeds ranging from 20,000-27,000 rpm, it has been found that, at these high speeds, the flow of oil to the splines is inadequate where the oil is allowed to merely pass over the splines. The apparent reason for this is that, at high speeds, the splines throw the oil outwardly and do not retain sufficient lubrication along the splined surfaces for prevention of wear, fretting and corrosion.